Firesnap

A Grace with the power to create fire. At the moment of conception, the fire is under their control. This means firesnaps may create a flame of any size and initially shoot it in any direction. However, immediately after the flame is created, they lose all control.
The name "firesnap" comes from the motion children are often taught to associate with using their power: the snap of their fingers. Since it's such a useful teaching method, even the most powerful firesnaps often use this trick to their dying day.

Dangers

Many young firesnaps are privy to burning down their villages. Oftentimes it goes something like this: they discover their power and get excited. They try to make it happen again to show their (increasingly jaded) brother/sister/parents/friends, but their excitement increases the magnitude of the flame they're trying to create, so the flame never actually creates - because now, the flame's potential magnitude would harm the other person upon creation, therefore breaking the first law. Dejected, the young mage slumps off to an abandoned barn, where they put so much effort into creating flame that, at the moment of creation, it bursts out from them at all angles and sets the barn on fire. Since the flame has been created, per rule 2, the firesnap no longer has control of the fire, and per rule 3, they can't simultaneously be a firedancer that can control the fire. So fire does as fire is and burns stuff.

Practical Uses

Most firesnaps wish to bring their power under control to decrease the magnitude of the flame created, to in turn decrease the magnitude of damage caused. Only well practiced firesnaps dare teach themselves to work with their flame in the moment of its creation - but the usefulness of massive fireballs are often lost, due to The Three Laws of Gracial Power.
Frequently, in combat, firesnaps and firedancers will team with a non-Grace. For example: a firesnap creates a flame, a firedancer leads it to an arrowhead to set it alight, and the non-Grace fires that arrow at another with the intention to harm. The fire was created with the intention of being used by the firedancer; the fire was controlled with the intention of lighting the arrow. The non-Grace then uses the arrow to harm another. As the flame on the arrow is not a direct use of Grace power to harm another, technically a Grace could be the one firing the arrow - but the two Graces of the trio are already exerting themselves to use their power, and bringing in a third Grace for a purpose other than using their power is a waste of resources. (That said, many Vinetuners make for highly sought-after archers, due to their ability to manipulate the wood of the bow and reduce the physical effort required to fire a shot.)